Method of and apparatus for comparing desired and actual values presented in digital form

ABSTRACT

Digitally represented desired and actual value series are plotted in graph form on a television screen for the purpose of comparison. The corresponding desired and actual values are shown in the same line of the picture so that the desired value curve and the actual value curve extend parallel to one another. In order to be able to predict the future course of the actual value curve, the desired value curve runs across the entire screen, while the actual value curve extends only across a part thereof. The most recent actual values are shown in a midportion of the screen. In this manner, desired values are shown for which no corresponding actual values are yet available.

Kurner et al.

United States Patent 91 METHOD OF AND APPARATUS FOR COMPARING DESIREDAND ACTUAL VALUES PRESENTED IN DIGITAL FORM Assignee:

Filed: Mar. 8, 1971 Appl. No.: 121,841

Siemens Aktiengesellschaft, Berlin and Munich, Germany ForeignApplication Priority Data Mar. 10, 1970 Germany Int. Cl.

Field of Search 340/324 A, 324 AD;

References Cited UNlTED STATES PATENTS ACTUAL VALUE MEMURY REAUUUTREGISTER 1 June 18, 1974 3,406,387 10/1968 Wcrme 340/324 A 3,474,43810/1969 3,487,308 12/1969 3,518,657 6/1970 3,522,597 8/1970 Murphy340/324 A Primary Examiner.1ohn W. Caldwell Assistant Examiner-MarshallM. Curtis Attorney, Agent, or Firm-Edwin E. Greigg [5 7] ABSTRACTDigitally represented desired and actual value series are plotted ingraph form on a television screen for the purpose of comparison. Thecorresponding desired and actual values are shown in the same line ofthe picture so that the desired value curve and the actual value curveextend parallel to one another. In order to be able to predict thefuture course of the actual value curve, the desired value curve runsacross the entire screen, while the actual value curve extends onlyacross a part thereof. The most recent actual values are shown in amidportion of the screen. In this manner, desired values are shown forwhich no corresponding actual values are yet available.

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METHOD OF AND APPARATUS FOR COMPARING DESIRED AND ACTUAL VALUESPRESENTED IN DIGITAL FORM BACKGROUND OF THE INVENTION This inventionrelates to a method of and apparatus for comparing actual and desiredvalues presented in digital form.

The usual way to proceed in the research technique is to measure allsignificant variables and to indicate the momentary values with analogor digital indicating instruments. The measured values of particularlyimportant variables are continuously recorded by means of dot or lineplotters to reveal the value variations as a function of time. In largeinstallations an instrumentation of this kind leads to such an expansionof control panels that the individual instruments, particularly in caseof a malfunctioning, may no longer be entirely supervised and themeasured values may be compared only with much difficulty.

Although the use of digital process calculators alleviates thesedifiiculties, it does not, however, effect a solution thereof. With acalculator all measured values of interest may be cyclically digitallymeasured and the digital values stored. It is sufficient hereby to storecompletely in a memory of short access time only the last measuredvalues which, for example, were sensed during a period of a few hours.For the indication of the momentaneous values, the memory locations arecalled and the measured values of interest may be digitally indicated orprinted. From such an indication, however, the variation of the measuredmagnitudes as a function of time may be established only withdifficulty. This is particularly disadvantageous if, for example, incase of a malfunctioning, the trend of the data series is to bedetermined rapidly. For such a purpose, an analog plotting issubstantially better adapted than a series of numerals, since a curvemay be evaluated much faster and easier.

It is known (as set forth, for example, in German Published Pat.applications DOS No. 1,808,245) to use for the analog representation ofmeasured values electronic analog visual apparatuses as readout devicesof digital calculators for the indication of alphameric signs or forproviding graphs wherein the curves are composed of dots on a screenwith the aid of an electron beam. In known processes, for therepresentation of a new value, the curve already displayed is shifted inthe direction of the time axis to provide a free location on the screenfor the new value. Thus, the curve slowly travels across the screen andthe newest measured value is always shown at the beginning of the curve.The oldest measured values disappear at the other screen edge.

OBJECT AND SUMMARY OF THE INVENTION The invention is based on theconsideration that an installation may be better operated if not onlythe current values are represented, but there is also shown acorresponding desired value curve consisting, for example, of themeasured values of the corresponding period of the previous day. Thecurves are so plotted that the desired values precede the actual values.In this manner the trend of the actual values is demonstrated and atimely interference may be effected concerning the course of theprocess.

Briefly stated, according to the invention, the actual and desiredvalues are represented as graphs on the screen of a television set andfurther, the actual and desired values corresponding to one another arerepresented in the same line of the television screen. Also, the desiredvalue curve extends across the entire area of the screen, whereas theactual value curve extends only over a part thereof. The newest actualvalues appear in a middle range of the screen area.

The invention will be better understood as well as objects andadvantages will become more apparent from the ensuing detailedspecification of several exemplary embodiments of the invention taken inconjunction with the drawing.

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a block diagram of anapparatus for practising the method according to the invention;

FIG. 2 is a circuit diagram of an image repeating memory for the desiredand actual values;

FIG. 3 is a block diagram of an arrangement to determine the moment ofrelease or readout of actual values with the aid of a shift counter;

FIG. 4 is a block diagram of a static image repeating memory;

FIG. 5 is a block diagram of a dynamic image repeating memory; and

FIGS. 6, 7 and 8 represent graphs of signal pulses to illustrate theoperation of the dynamic image repeating memory shown in FIG. 5.

DESCRIPTION OF THE EMBODIMENTS Turning now to FIG. 1, there is shown avideo apparatus l which receives signals from a pulse central 2. Theapparatus 1 and the pulse central 2 are components of a commerciallyavailable conventional industrial television system. The pulse central 2may be replaced by a light intensity amplifier which produces, from thedigital light-dark signals, the signal (containing the image pulse,blanking pulse and synchronizing pulse) for the control of the videoapparatus. The camera of the television system is replaced by a counter20 (controlled by a beat generator 5), by two comparator circuits 23 and24 which compare the contents of the counter 20 with the contents of tworeadout registers 21 and 22 and by two image repeating memories 4 and 4'which control the readout registers 21 and 22. There is further providedan address or line counter 17 and a scale-down circuit 6. The latterforms, from the beatfrequency, the horizontal and the vertical scanningfrequencies of the electron beam of the video apparatus 1 and controlsthe pulse central 2. There is further provided a work memory 7 which isassociated with a process calculator and in which there are storedseries of measured values from various measuring stations. If measuredvalues from a certain measuring station are to be represented, thenfirst the corresponding memory range of the process calculator has to becalled. This is performed in the usual manner by giving a command byoperating an appropriate control panel. Thereupon the process calculatortransfers the measured values from the work memory 7 to the imagerepeating memories 4 and 4'. The number of the measured values isadapted to the storage capacity of the image repeating memories. Aftertermination of the aforenoted transfer which, dependent upon the type ofthe image repeating memories 4 and 4 and the work memory 7, lasts a fewmilliseconds at the most, the measured values are, during normaloperation, cyclically transmitted from the image repeating memories 4and 4' to the readout registers 21 and 22, respectively. The contents ofthese registers are compared in the comparator stages 23 and 24 with thecontents of the counter 20. The latter counts upwardly by means of thebeat pulses, with each line pulse as a start signal. Upon reaching theterminal position, it resets itself automatically and an admission offurther beat pulses is blocked until a new start signal, that is, thesuccessive line return pulse, appears. If one of the two comparatorstages 23 and 24 determines that the counter position is identical tothe contents of a readout register, then it delivers a light pulsesignal to the pulse central 2. Since the counter 20 counts through fromuntil the terminal value, it is capable to pick up all values of datawords in one series of counting. With such an arrangement, two curvesmay be simultaneously represented on the screen. The address counter 17to which the horizontal deflecting pulses of the scale-down circuit 6are applied, controls the inscription and readout into and from theimage repeating memories 4 and 4'.

One of the two curves shown on the screen is the desired value curve,while the other is the actual value curve. The desired values may be,for example, the corresponding actual values of the previous day. Eachdesired value and its corresponding actual value should appear in thesame line of the television picture. Therefore, the desired and actualvalues corresponding to one another are introduced in the same addressesof the memories 4 and 4'. If both memories are filled with values, thenthe newest actual value appears at the upper edge of the screen fieldstanding by for the signal representation. Upon arrival of a new actualvalue, to which there corresponds a desired value still contained in thework memory 7, both curves are shifted by one line downwardly and thenewest actual value and the associated desired value are introduced inthe uppermost line. This method lends itself only to a comparison fordetermining to what extent the desired and actual values differ from oneanother. For the control of a process frequently it is much moreadvantageous to also know how the actual values will presumably changein the future. For this purpose even those desired values are utilizedfor which no corresponding actual values are still in existence. If thedesired values are contained in the memory 4', then a determined numberof additional desired values is introduced thereinto in such a mannerthat the addresses of the already stored desired values are increased byl and the new desired value is introduced into the memory cell with thelowest address. In this manner the desired value curve is shifted on thescreen downwardly. Simultaneously, the addresses of the actual values inthe memory 4 are also changed so that the beginning of the actual valuecurve is shifted downwardly on the screen of the video apparatus 1. If,for example, 200 lines are available for the representation of thecurves and 100 additional desired values are inscribed, then the actualvalue curve begins in the middle of the screen. It is here assumed thatfor each actual value there exists a corresponding desired value.Otherwise, the corresponding desired value has to be first calculated.If a new actual value appears, then the latter is represented in themiddle of the picture screen after the actual value curve has beenshifted downwardly by one line. Simultaneously, a desired value is addedto the desired value curve at the upper edge of the screen. Thus, bothcurves travel simultaneously downwardly with identical speed. The twocurves have, in principle, a configuration shown in FIG. 1 on the screenof the video apparatus l. The right-hand curve which extends across theentire screen is the desired value curve while the lefthand curve whichbegins in the middle of the screen is the actual value curve.

In FIG. 2 there are shown exemplary circuits constituting the imagerepeating memories 4 and 4. Basically, they comprise shift registers 41,41' and 42 in feedback connection. The shift registers containinscribing and readout registers 9, 9 and 10. After calling of thevalues from the work memory 7 of the process calculator, first the twomemories are filled, for example, with 200 measured values each.Thereafter, additional values, for example, lOO in number, areintroduced into the desired value memory. The shift registers 41' and 42of the actual value memory 4 receive, for example, measured values each.Upon introduction of the 100 desired values, the values in the register41' are shifted into the register 42 while the values in the register 42are erased. Therefore, upon reproduction of the contents of bothmemories, the desired value curve extends across the entire screen whilethe actual value curve extends only across the lower portion thereof.The inscription of new desired and actual values in then controlled insuch a manner that the desired values are inscribed through theinscribing register 9 in the shift register 41 while the actual valuesare inscribed through the inscribing register 10 in the shift register42. The image repeating memory 4 may consist only of the shift register42. in such a case the contents of the register 42 circulate twiceduring an image reproduction. During the first lap, the electron beamhas to be controlled dark" for the actual value curve. This is achievedsimply by blocking the output signal of the comparator 23 during thefirst lap of the circulating signal pulses. Such blocking may becontrolled, for example, by the address counter 17. Accordingly, it isalso possible not to extinguish the actual values already in theregister 42 during inscription into the latter of the last l00 actualvalues, but to shift them into the shift register 41' and upon theirreproduction to modulate the electron beam dark."

in the apparatuses described hereinabove, the lead of the desired valuecurve with respect to the actual value curve may be varied only withdifficulty. HO. 3 illustrates an arrangement by means of which such alead may be varied at will. The information lNF for the tie sired valuememory 4 and for the actual value memory 4 is directed through aninscription control 16. The latter delivers the stepping pulses for theaddress and line counter 17, which, in turn, emits control pulses forthe introduction and release of values into and from the memories 4 and4'. With each desired value which is introduced into the memory 4' thereis given a stepping pulse to a shift counter 19. A comparator l8 emits astarting signal for the readout of the actual values and for the momentof inscription of new actual values. If, for example, after bothmemories 4 and 4 are filled, an additional 50 desired values aretransferred into the memory 4', then the shift counter 19 has reachedthe count 50, provided it was previously set to zero. The line counter17 which is set to zero with the image return pulses, reaches theposition 50 with the fiftieth line of an image, and the comparator 18transmits a control signal to the inscription control 16 which, in turn,emits a command signal for the readout of the actual values from thememory 4. The newest actual value will therefore appear in line 50 or51. In order to ensure that the beginning of the curves does not lieabove the upper edge of the screen, the uppermost values of the curvesare represented not in the first line but in a line of a higher order,for example, 51, so that the shift counter 19 is reset not to zero butto a higher number, for example, 51. The pulses, for example 50 innumber, which the shift counter 19 summarizes upon inscription ofadditional desired values, are added to the preset number so that in theexample, the newest actual value is represented in line 101.

The apparatus shown in FIG. 3 is adapted to compare two series ofmeasured values plotted in the past. For this purpose, the two measuredvalue series are again inscribed in the memories 4 and 4'. In order tobe able to better compare the curves with one another, they should berelatively shiftable. For this purpose, the shift counter 19 is notswitched when desired values are inscribed in the memory 4', but thereis provided a beat generator 25 by means of which the position of thecounter 19 can be varied. For the fine adjustment, the stepping pulsesmay be individually triggered in a manual manner, but, for a rapid shiftof the desired value curve, they may be produced in a generator with anoutput frequency of, for example, cycles. In order to ensure that thedesired value curve is shiftable in both directions, the counter 19should be a forward and backward counter.

Turning now to FIG. 4, there is shown an extension of the arrangementillustrated in FIG. 3. In addition to the shift counter 19, thecomparator 18 and the line counter 17, there is provided a second shiftcounter 27 and a comparator stage 26 which, in case of an identicalposition of counters l7 and 27, transmits a switch signal to one inputof a trigger pair circuit BK, the other input of which of which iscontrolled by the comparator stage 18. This trigger pair circuit isincorporated in the inscription control designated with 16 in FIG. 3.From its output there is applied a release signal to a gate circuit T,to the other input of which there are applied the shift beat pulses forthe actual value memory 4 which here again is expediently designed as ashift register. In the present case, the latter should be able to storeonly as many values as there are lines in the screen field where thecurves are to be plotted. In any case, it has to be ensured that theshift register circulates only once during the reproduction of an image.This purpose is served by the counter 27 which in this embodiment is setto a number which, corresponding to the line number in the screen field,is by 200 higher than the number to which the counter 19 is preset. If,for example, the counter 19 is in position 51, then the counter 27 is inposition 251. If then, there are introduced I00 values more into thedesired value memory than into the actual value memory, the counter 19will be in position 151 and the counter 27 in position 37 because, uponreaching position 314 which corresponds to the total number of lines inthe image, it resets itself to 1. Upon reproduction of an image,accordingly, the trigger pair circuit BK, upon inscription of the onehundred fiftyfirst line, is switched and the gate T is set free for theshift beat pulse. The frequency of this beat pulse has a fixedrelationship with respect to the line frequency to ensure that onedesired value and one actual value is shifted into the readout registerof the memories during a line period. After the scanning of 200 lineswith the gate T open, the line counter reaches the count 37, thecomparator 26 responds and switches the trigger pair circuit BK so thatthe gate T is again closed. Thus, in case of a storage capacity of 200actual values, the values have circulated the memory exactly once. Whenthe line counter again reaches count 151, the gate T is again opened andthe first actual value is indicated in the one hundred fifty-first line.The arrangement; according to FIG. 4, serves for the control of thecirculation of the actual values in the image repeating memory. Thearrangement for the control of the circulation of the desired values intheir circulation memory is similarly designed except that only a singlecounter is required for the beat pulses. To this counter there areconnected two comparators of which one switches, at counter position 51,a trigger pair circuit, which at the counter position 251 is switchedback by the other comparator. In the meantime a gate is opened for thebeat pulses which shift the desired values in the image repeatingmemory.

Upon inscription of new desired and actual values, the oldest valueshave to be removed from the memories and replaced by the newest valueswhereby the newest values have to be represented at the beginning of thecurve. Upon inscription of a new desired value in the desired valuememory, the gate is closed when the shift counter reaches the position250. The two hundred fifty-first measured value may then be written overwith the newest value if at that moment the oldest measured value is inthe inscribing and readout register. During the next lap, only thenewest value can be represented in the line 51; it joins the curve atthe upper screen edge. Simultaneously in order to ensure that bothcurves retain the same time relation the actual value curve also has tobe provided at its beginning with its newest value. This is effected inthe same manner as the introduction of the newest desired value, byclosing the gate circuit T one line earlier for the best pulses whichcontrol the actual value memory. This is achieved by resetting by l thecounter 27 (which is a forward and backward counter) and returning it toits old position after inscription of the new value.

In order to ensure that no actual values are represented in the imageportion in which the desired value curve has a lead with respect to theactual value curve, in this portion the light intensity modulation forthe actual value curve is turned off. The signal therefor may beobtained by superposition of the output signal of the trigger paircircuit BK with the signal which indicates the end (i.e., line 252) ofthe screen range used for the reproduction. Thus, light intensitymodulation of the actual values occurs only from the starting moment forthe shift pulses until line 251.

In the arrangement according to FIG. 4, circulation memories are usedwhich may be arrested for a while and then may be restarted. Very often,however, the use of circulation memories should be possible in which thedata circulate in a continuous manner. Such memories are, for example,plate, drum, or transit time memories. More recently, dynamic shiftregisters have been developed in the integrated MOS-technique which havea large capacity and small space requirement, but which require shiftbeat pulses with a minimum frequency below which the stored informationmay be lost. If the capacity of such a shift register is selected to beexactly of such a magnitude that the information to be represented mayjust be stored therein, then after the readout of the last word of areproducing cycle the shift beat frequency must be blocked until thelast image is inscribed. During such a period, however, the stored datamay be lost. In FIG. there is shown the basic circuit diagram of anarrangement in which such image repeating memories may be used.Reference numerals 4 and 4' again indicate the desired value memory andthe actual value memory, respectively. Since dynamic shift registershave to receive shift beal pulses continuously, the new measured valuescannot be inscribed at an arbitrary moment between the reproduction ofthe last and the first represented measured values as it was possible,for example, in the arrangement according to FIG. 4. Thus, a newmeasured value is inscribed in the circulating shift register at amoment when the line counter 17 reaches the count or the address, as thecase may be, of the memory cell in which the newest measured value hasto be inscribed. This, for the desired value memory, is the measuredvalue address 0 which in the present case corresponds to the line 50. Atake-over pulse for the desired value memory thus occurs alwayssynchronously with the writing of the line 50. The position 50 of theline counter 17 is determined by a line counter evaluating circuit 31which then transmits a signal to the inscription control 16. Theevaluation of the line counter position 50 also applies to the actualvalue memory if to the newest measured value thereof there is assignedthe measured value address 0. This corresponds to a presetting of theshift counter 19 to the value 50. The evaluation is, however, taken overby the comparator 18. The representation of the measured values occursfrom the measured value address 1, the content of which is representedin line 51. In order to complement the measured value curve in theafore-described manner with the newest measured values, the introducedmeasured values have to be re-addressed by one position after eachinscription.

In the pulse diagram according to FIG. 6, the simultaneous inscriptionof desired and actual values is illustrated for the case when theinscribed values are to be represented in the same line. Uponinscription of a measured value in the memory cell of the desired valuememory with the address 0, the addresses of all memory cells areincreased by I so that the newest measured value will be represented inline 51. The same process takes place in the actual value memory if thenewest value thereof is to be represented in the same line as the newestdesired value.

In the description that follows, there will be set forth, with referenceto the pulse diagram according to FIG. 7, how a lead of the desiredvalue curve is effected with respect to the actual value curve by meansof inscription of desired values. If desired values are introduced intothe desired value memory as lead, then, on the one hand, take-overpulses UEB l are counted in the shift counter 19 and, on the other hand,signals MOD 1 and MOD 2 which effect the re-addressing in the desiredvalue memory and in the actual value memory, are applied to bothmemories. In this manner the actual values are re-addressed by as manypositions as there are advance desired values that were entered. Thenewest actual value is contained in that memory cell of the actual valuememory, the address of which is determined by the position of the shiftcounter 19.

FIG. 8 illustrates a pulse diagram for the simultaneous inscription ofdesired values and actual values in the case when the desired valuecurve has a lead with respect to the actual value curve. ln thisinstance, the take-over pulses UEBl and UEB 2 arrive at differentmoments. The signal UEB I for the desired values arrives synchronouslywith the line 50, and the readdressing signal MOD 1 for the desiredvalue memory begins with the address 0. The take-over signal UEB 2, onthe other hand, arrives at a later moment, because it is generated onlywhen the line counter 17 has reached the position of the shift counter19. The readdressing signal MOD 2 for the actual value memory beginsonly after the arrival of the take-over signal UEB 2.

The choice among the three inscribing methods may be made by thecalculator which introduces the corresponding indications into afunction register 30 which, in turn, effects the routing of the pulseswithin the inscription control. If the actual value curve is erasedthrough the function register, then, from this occurrence a resettingpulse is derived which returns the shift counter 19 to position 50.

A further operating mode may be desirable in a case set forthhereinbelow. The represented desired value of the previous day may have,for example, a particular course at a determined period. If the actualvalue curve shows a trend of a similar course, but for another point intime, then it is advantageous to be able to shift the curves in such amanner that the similar courses of the curves are disposed adjacent orin superposition with respect to one another. For this purpose, theshift counter 19 is formed as a forward and backward counter. Theattendant may now apply counting pulses through the function register 30to the shift counter 19, and simultaneously apply, in an identicalnumber, addressing signals to the actual value memory. In response, theactual value curve shifts on the screen in the desired direction. If,subsequently, the newest measured values are introduced, then, again,the inscription address is determined for the actual values by theposition of the shift counter 19.

What is claimed is:

l. A method of comparing digitally presented actual and desired values,comprising the steps of A. displaying a series of desired values as acurve extending across the entire field of a television screen,

B. displaying a series of actual values as a curve extending solelyacross one part of said field,

C. adding the newest actual values to the actual display of the valuecurve at a midportion of said field and D. orienting the respectivecurves so that mutually corresponding actual and desired values aredisplayed in the same and-raster line of the television picture.

2. A method as defined in claim 1, including the steps A. inscribing, atthe beginning of curve representation, the desired values and the actualvalues in two separate and similar image repeating memories; mutuallycorresponding actual and desired values are inscribed in memory cellswith the same address,

B. cyclically applying said actual and desired values from said imagerepeating memories to a video apparatus including said televisionscreen,

C. subsequently inscribing a predetermined amount of desired values inthe image repeating memory for desired values,

D. shifting the actual values in said image repeating actual valuememory with respect to the addresses by the same amount andextinguishing the same amount of actual values inscribed thereinsubstantially contemporaneously with said step of subsequentlyinscribing,

E. shifting the stored actual and desired values by one memory locationfor inscribing new actual and desired values,

F. inscribing the new desired value in the vacated memory location withthe lowest address and G. inscribing the new actual value in the vacatedmemory location with an address higher than that assigned to theprevious most recent actual value.

3. A method as defined in claim 1, including the steps A. inscribing, atthe beginning of curve representation, the desired values and the actualvalues in two separate and similar image repeating memories; mutuallycorresponding actual and desired values are inscribed in memory cellswith the same address, I

B. cyclically applying said actual and desired values from said imagerepeating memories to a video apparatus including said televisionscreen,

C. subsequently inscribing a predetermined amount of desired values inthe image repeating memory for desired values,

D. shifting, simultaneously with the step set forth precedingly, theactual values in the image repeating memory for actual values withrespect to the addresses by the same amount,

E. modulating dark" the electron beam plotting said curves on thetelevision screen upon representation of the contents of the memorycells with the addresses by which the newest actual value has beenshifted,

F. shifting the stored actual and desired values by one memory locationfor inscribing new actual and desired values,

G. inscribing the new desired value in the vacated memory location withthe lowest address and H. inscribing the new actual value in the vacatedmemory location with an address higher than that assigned to theprevious most recent actual value.

4. A method as defined in claim 1, including the steps of A. inscribing,at the beginning of curve representation, the desired values and theactual values in two separate and similar image repeating memories;mutually corresponding actual and desired values are inscribed in memorycells with the same address,

B. cyclically applying said actual and desired values from said imagerepeating memories to a video apparatus including said televisionscreen,

C. subsequently inscribing a predetermined amount of desired values inthe image repeating memory for desired values,

D. shifting, simultaneously with the step set forth precedingly, theactual values in said image repeating memory for actual values withrespect to the addresses by the same amount and extinguishing the sameamount of actual values inscribed therein.

E. shifting the stored actual and desired values by one memory locationfor inscribing new actual and desired values,

F. inscribing the new desired value in the vacated memory location withthe lowest address,

G. inscribing the new actual value in the vacated memory location withan address higher than that assigned to the previous most recent actualvalue,

H. counting by means of a shift counter and without a simultaneousinscription of actual values in the image repeating memory for actualvalues the number of desired values introduced into the image repeatingmemory for the desired values,

I. comparing the contents of said shift counter with the contents of aline counter and J. beginning the representation of the actual valueswhen identity between the contents of said shift counter and said linecounter is reached.

5. A method as defined in claim 1, including the steps A. inscribing, atthe beginning of curve representation, the desired values and the actualvalues in two separate and similar image repeating memories; mutuallycorresponding actual and desired values are inscribed in memory cellswith the same address,

B. cyclically applying said actual anddesired values from said imagerepeating memories to a video apparatus including said televisionscreen,

C. subsequently inscribing a predetermined amount of desired values inthe image repeating memory for desired values,

D. shifting, simultaneously with the step set forth precedingly, theactual values in the image repeating memory for actual values withrespect to the addresses by the same amount,

E. modulating dark" the electron beam plotting said curves on thetelevision screen upon representation of the contents of the memorycells with the addresses by which the newest actual value has beenshifted,

F. shifting the stored actual and desired values by one memory locationfor inscribing new actual and desired values,

G. inscribing the new desired value in the vacated memory location withthe lowest address,

H. inscribing the new actual value in the vacated memory location withan address higher than that assigned to the previous most recent actualvalue,

I. counting, by means of a shift counter, and without a simultaneousinscription of actual values in the image repeating memory for actualvalues the number of desired values introduced into the image repeatingmemory for the desired values,

J. comparing the contents of said shift counter with the contents of aline counter and K. beginning the representation of the actual valueswhen identity between the contents of said shift counter and said linecounter is reached.

6. An apparatus for comparing actual and desired values comprising:

A. a video apparatus including a picture screen,

B. an image repeating memory for actual values,

C. an image repeating memory for desired values; the number of memorycells in each memory being less than the number of lines in thetelevision picture on said screen,

D. a line counter,

E. a trigger pair circuit,

F. a shift counter,

G. a first comparator circuit transmitting a setting signal to saidtrigger pair circuit when the contents of said shift counter and saidline counter are identical,

H. a further counter controlled parallel with said shift counter andpreset to a number which is greater by the number of memory cells thanthe number to which said shift counter is set,

. a second comparator circuit transmitting a resetting signal to saidtrigger pair circuit when the contents of said line counter and saidfurther counter are identical and .l. a gate circuit connected to saidtrigger pair circuit and opened by the latter when in a set position toaliow passage of shift beat pulses to said image repeating memory foractual values.

7. An apparatus for comparing actual and desired values comprising:

B. an image repeating memory for actual values,

C. an image repeating memory for desired values; the number of memorycells of the memories being larger than the number of values to bestored and, at the most, being identical to the number of lines in thepicture on said television screen,

D. a line counter,

E. a shift counter,

F. comparison circuit means coupled to respective outputs from said linecounter and said shift counter for producing a control signal wheneverthe outputs from said line counter and said shift counter are equal, and

G. an inscription control circuit means coupled from said comparisoncircuit means and to each of said image repeating memories, to an inputof said line counter and to an input of said shift counter fortransmitting to effect the inscription of a desired value and an actualvalue, a take-over signal to said image repeating memory for desiredvalues and to said shift counter at the moment when the line is writtenin which the first value of the desired value curve is plotted and fortransmitting a take-over signal, in response to the control signal fromsaid comparison circuit means, to said image repeating memory for actualvalues when the contents of said line counter and said shift counterbecome identical

1. A method of comparing digitally presented actual and desired values,comprising the steps of A. displaying a series of desired values as acurve extending across the entire field of a television screen, B.displaying a series of actual values as a curve extending solely acrossone part of said field, C. adding the newest actual values to the actualdisplay of the value curve at a midportion of said field and D.orienting the respective curves so that mutually corresponding actualand desired values are displayed in the same and-raster line of thetelevision picture.
 2. A method as defined in claim 1, including thesteps of A. inscribing, at the beginning of curve representation, thedesired values and the actual values in two separate and similar imagerepeating memories; mutually corresponding actual and desired values areinscribed in memory cells with the same address, B. cyclically applyingsaid actual and desired values from said image repeating memories to avideo apparatus including said television screen, C. subsequentlyinscribing a predetermined amount of desired values in the imagerepeating memory for desired values, D. shifting the actual values insaid image repeating actual value memory with respect to the addressesby the same amount and extinguishing the same amount of actual valuesinscribed therein substantially contemporaneously with said step ofsubsequently inscribing, E. shifting the stored actual and desiredvalues by one memory location for inscribing new actual and desiredvalues, F. inscribing the new desired value in the vacated memorylocation with the lowest address and G. inscribing the new actual valuein the vacated memory location with an address higher than that assignedto the previous most recent actual value.
 3. A method as defined inclaim 1, including the steps of: A. inscribing, at the beginning ofcurve representation, the desired values and the actual values in twoseparate and similar image repeating memories; mutually correspondingactual and desired values are inscribed in memory cells with the sameaddress, B. cyclically applying said actual and desired values from saidimage repeating memories to a video apparatus including said televisionscreen, C. subsequently inscribing a predetermined amount of desiredvalues in the image repeating memory for desired values, D. shifting,simultaneously with the step set forth precedingly, the actual values inthe image repeating memory for actual values with respect to theaddresses by the same amount, E. modulating ''''dark'''' the electronbeam plotting said curves on the television screen upon representationof the contents of the memory cells with the addresses by which thenewest actual value has been shifted, F. shifting the stored actual anddesired values by one memory location for inscribing new actual anddesired values, G. inscribing the new desired value in the vacatedmemory location with the lowest address and H. inscribing the new actualvalue in the vacated memory location with an address higher than thatassigned to the previous most recent actual value.
 4. A method asdefined in claim 1, including the steps of A. inscribing, at thebeginning of curve representation, the desired values and the actualvalues in two separate and similar image repeating memories; mutuallycorresponding actual and desired values are inscribed in memory cellswith the same address, B. cyclically applying saiD actual and desiredvalues from said image repeating memories to a video apparatus includingsaid television screen, C. subsequently inscribing a predeterminedamount of desired values in the image repeating memory for desiredvalues, D. shifting, simultaneously with the step set forth precedingly,the actual values in said image repeating memory for actual values withrespect to the addresses by the same amount and extinguishing the sameamount of actual values inscribed therein. E. shifting the stored actualand desired values by one memory location for inscribing new actual anddesired values, F. inscribing the new desired value in the vacatedmemory location with the lowest address, G. inscribing the new actualvalue in the vacated memory location with an address higher than thatassigned to the previous most recent actual value, H. counting by meansof a shift counter and without a simultaneous inscription of actualvalues in the image repeating memory for actual values the number ofdesired values introduced into the image repeating memory for thedesired values, I. comparing the contents of said shift counter with thecontents of a line counter and J. beginning the representation of theactual values when identity between the contents of said shift counterand said line counter is reached.
 5. A method as defined in claim 1,including the steps of A. inscribing, at the beginning of curverepresentation, the desired values and the actual values in two separateand similar image repeating memories; mutually corresponding actual anddesired values are inscribed in memory cells with the same address, B.cyclically applying said actual and desired values from said imagerepeating memories to a video apparatus including said televisionscreen, C. subsequently inscribing a predetermined amount of desiredvalues in the image repeating memory for desired values, D. shifting,simultaneously with the step set forth precedingly, the actual values inthe image repeating memory for actual values with respect to theaddresses by the same amount, E. modulating ''''dark'''' the electronbeam plotting said curves on the television screen upon representationof the contents of the memory cells with the addresses by which thenewest actual value has been shifted, F. shifting the stored actual anddesired values by one memory location for inscribing new actual anddesired values, G. inscribing the new desired value in the vacatedmemory location with the lowest address, H. inscribing the new actualvalue in the vacated memory location with an address higher than thatassigned to the previous most recent actual value, I. counting, by meansof a shift counter, and without a simultaneous inscription of actualvalues in the image repeating memory for actual values the number ofdesired values introduced into the image repeating memory for thedesired values, J. comparing the contents of said shift counter with thecontents of a line counter and K. beginning the representation of theactual values when identity between the contents of said shift counterand said line counter is reached.
 6. An apparatus for comparing actualand desired values comprising: A. a video apparatus including a picturescreen, B. an image repeating memory for actual values, C. an imagerepeating memory for desired values; the number of memory cells in eachmemory being less than the number of lines in the television picture onsaid screen, D. a line counter, E. a trigger pair circuit, F. a shiftcounter, G. a first comparator circuit transmitting a setting signal tosaid trigger pair circuit when the contents of said shift counter andsaid line counter are identical, H. a further counter controlledparallel with said shift counter and preset to a number which is greaterby the number of memory cells than the number to Which said shiftcounter is set, I. a second comparator circuit transmitting a resettingsignal to said trigger pair circuit when the contents of said linecounter and said further counter are identical and J. a gate circuitconnected to said trigger pair circuit and opened by the latter when ina set position to allow passage of shift beat pulses to said imagerepeating memory for actual values.
 7. An apparatus for comparing actualand desired values comprising: A. a video apparatus including a picturescreen, B. an image repeating memory for actual values, C. an imagerepeating memory for desired values; the number of memory cells of thememories being larger than the number of values to be stored and, at themost, being identical to the number of lines in the picture on saidtelevision screen, D. a line counter, E. a shift counter, F. comparisoncircuit means coupled to respective outputs from said line counter andsaid shift counter for producing a control signal whenever the outputsfrom said line counter and said shift counter are equal, and G. aninscription control circuit means coupled from said comparison circuitmeans and to each of said image repeating memories, to an input of saidline counter and to an input of said shift counter for transmitting toeffect the inscription of a desired value and an actual value, atake-over signal to said image repeating memory for desired values andto said shift counter at the moment when the line is written in whichthe first value of the desired value curve is plotted and fortransmitting a take-over signal, in response to the control signal fromsaid comparison circuit means, to said image repeating memory for actualvalues when the contents of said line counter and said shift counterbecome identical.